Question

我想创建一个抽象类，它将调用Dao来插入任何实体对象，以避免在实现IRepository的每个类中编写重复的代码，

public abstract class DBStore<T> implements IRepository {
    DaoMaster daoMaster;
    Class<T> entityClass; 

    public DBStore(DaoMaster daoMaster, Class<T> entityClass) {
        this.daoMaster = daoMaster;
        this.entityClass = entityClass;
    }

    @Override
    public void add(Entity entity) {
        DaoSession session = this.daoMaster.newSession();
        AbstractDao<?, ?> dao = session.getDao(this.entityClass);
        dao.insert(entity);  // cannot pass entity as parameter because insert() expects capture<?>
    }

    // Other CRUD methods
}

我不明白我应该使用什么语法来指定变量entity是insert()所期望的。

Answer 1

好的，我通过指定DBStore<T extends Entity> implements IRepository<T>来实现它并将AbstractDao<?, ?>投射到AbstractDao<T, Long>

以下是完整的代码：

public abstract class DBStore<T extends Entity> implements IRepository<T> {
    DaoMaster daoMaster;
    Class<T> entityClass;

    public DBStore(DaoMaster daoMaster, Class<T> entityClass) {
        this.daoMaster = daoMaster;
        this.entityClass = entityClass;
    }

    @Override
    public void add(T entity) {
        this.getSession().insert(entity);
    }

    @Override
    public T getById(long id) {
        AbstractDao<T, Long> dao = this.getDao();
        return dao.load(id);
    }

    //other methods

    protected AbstractDao<T, Long> getDao(){
        DaoSession session = this.daoMaster.newSession();
        return (AbstractDao<T, Long>) session.getDao(this.entityClass);
    }

    protected DaoSession getSession(){
        return this.daoMaster.newSession();
    }
}

如何创建一个抽象类，使用GreenDAO为任何实体模型处理基本CRUD

1 个答案: